The subject invention relates generally to an interactive accessory for use with a video display. One particular aspect of the invention is the provision of a hardware interface between the user and a video cassette recorder band playback system using prerecorded video tapes (software).
The very large and still rapidly growing installed base of video cassette recorders (VCR's) worldwide in the mid-1980s has spurred interest in interactive home video systems.
It has become apparent to the inventors that an acceptable system for interaction with a home video display requires a suitable feedback loop between the operator and television screen. Apparatus providing such feedback further must allow for interaction at a considerable distance from the television screen and should not contain visual or operational nuances which annoy, distract or otherwise obstruct or discourage use by the viewer.
It is further desirable in such a system to provide "branching," i.e., the capability for selection of one of a number of video pictures and/or audio responses based upon user decision.
As is well known, the linear nature of the presentation obtained from an ordinary consumer-type of video tape player makes rapid branching to various segments of the tape an impossibility. While many VCR's provide features such as rapid forward and reverse search modes, there are still far too slow for branching in interactive game or learning environments.
A number of reasonably satisfactory solutions leading to rapid visual branching have nevertheless been proposed in the prior art and actually used with some success in experimental or commercial equipment. However, a successful interactive system requires not only visual branching but audio branching as well. Again, the availability of two audio tracks in some VCR's would permit two-way branching. Such branching proves marginally adequate in such applications as tutorial quizzes where audio branching responses can be limited to alternate sets such as "yes, you were right" and "No, your were wrong," or the like. However, instantaneous audio branching to four or more audio responses is mandatory to provide audio accompaniment for more complex visual branching schemes. Attainment of such capability requires a technique other than conventional sound "track" recording. Another obstacle to providing a large number of selectable audio responses is the necessity for an inexpensive audio encoding technique which is compatible with the limited bandwith of commercially available VCR equipment. Such equipment typically has a bandwith on the order of two megahertz (MHz). The limitations posed by such limited bandwith are indicated in part by the fact that such VCR equipment typically demodulates the color subcarrier of a standard television signal to a lower frequency and then remodulates it, resulting in color degradation of the VCR output. Audio encoding must cope not only with this obstacle, but also with discontinuities present in the television signal which can cause further degradation of audio performance.